Background: Infants exposed to methadone during pregnancy experience high rates of neonatal abstinence syndrome (NAS). Common NAS symptoms (tremulousness, increased muscle tone, sweating, excessive crying, vomiting and diarrhea) increase infants'metabolic needs. Another frequent NAS symptom, weak and uncoordinated suckling, impairs infants'ability to take in adequate calories. These combined problems compromise infant weight gain. The current standard of care for opiate-exposed infants requires evidence of poor weight gain or excessive weight loss before initiating high-calorie formula. We hypothesize that inadequate caloric intake among methadone exposed infants may result in excessive weight loss, slow weight regain and exacerbation of NAS. These factors lead to the newborn's requirement for higher morphine doses and longer duration of hospitalization. Therefore, methadone exposed infants may benefit from early caloric enhancement. A nutritional intervention for opiate-exposed infants has not been previously evaluated. This application will provide data on adequacy of recruitment, protocol feasibility, performance of selected measures, and preliminary estimates of efficacy for a comprehensive R01 submission. Specific Aims: 1. For methadone exposed infants, compare infants randomized to high (24 kcal/oz) versus standard (20 kcal/oz) formula for the following outcomes: Weight loss and gain patterns. The primary dependent measure will be days until the infant returns to birth weight. Secondary measures will be maximum percent weight loss and days to weight nadir. NAS severity measured by: a) total length of hospital stay for NAS;b) duration of NAS treatment;c) mean Finnegan scores on days 2-10;d) maximum concentration of morphine used to treat NAS. 2. Describe the suck quality at 4-6 days of age among methadone exposed infants. Evaluate the association between the infant suck quality and infant weight loss and gain patterns and measures of NAS severity. Design: Women on methadone will be recruited during pregnancy and will attend a single brief visit late in pregnancy. After delivery, infants will be randomized in a double blind trial of either high-calorie or standard- calorie formula which will be started at 72 hours after birth and be continued through 21 days of age. Infants will be weighed daily and will have outpatient study visits at 1 and 3 months. For this pilot study, up to 70 mothers will be enrolled over 18 months. This pilot study is needed to establish the feasibility of the study methods and to better estimate differences that can be observed between the groups. For the primary outcome variable, days until the infant returns to birth weight, discrete survival methods will be used. Potential Impact: Early caloric enhancement for methadone-exposed infants is inexpensive, readily available, easy to implement and could improve outcomes of these high-risk infants. High-calorie formula could result in a more normal pattern of weight loss and gain, less severe NAS symptoms and shorter hospital stays. PUBLIC HEALTH RELEVANCE: Neonatal abstinence syndrome (NAS) symptoms contribute to poor infant weight gain. Early caloric enhancement for infants exposed to methadone is inexpensive, readily available, easy to implement and could improve early outcomes for these high-risk infants. We will conduct a preliminary randomized clinical trial of high-calorie vs. standard-calorie formula for methadone exposed infants to evaluate the adequacy of recruitment, protocol feasibility and estimates of whether high-calorie formula results in more normal patterns of weight loss and gain, less severe NAS symptoms and shorter hospital stays.